The invention relates to an power tool having an electric motor for driving a tool, having a motor shaft, having a stator, having an armature and having a commutator with brushes.
An power tool such as this is known, for example from WO 01/51251 A1 which corresponds to U.S. Ser. No. 2002/0151262 A2. The known power tool is an angle grinder with a universal motor which has a fan at its end facing the tool, and has a commutator with brushes at the opposite end. The angle grinder is surrounded by a housing on which the bearing for the motor shaft, a tool head for driving the tool, the brushes, switches and the like are held.
Power tools such as these have been known for many years.
Normally, power tools are driven by universal motors. A universal motor normally has a housing within which a stator with pole field windings is provided, within which an armature is arranged such that it can rotate. The armature is held on a motor shaft, which is mounted by means of bearings on the housing such that it can rotate. Furthermore, a universal motor has a fan which is provided at a first end of the armature, and has a commutator with brushes, which is provided at the other end of the armature.
Owing to the high power/weight ratio and the capability to use them universally with direct current and with alternating current, universal motors such as these have been proven for driving power tools. As before, power tools are subject to the requirement for weight reduction, for an increase in power and for a reduction in the physical size for the same power. Furthermore, rationalization efforts are continuously resulting in the requirements for a design which is as simple and cost-effective as possible and for simple installation. Furthermore, reliability that is as high as possible is desired, even for use in continuous operation.
Power tools having a housing in the form of a rod always have a specific shaft diameter for a specific power class, thus resulting in a specific minimum diameter for a rod housing, owing to the necessity for the commutator and the associated brushes. If it is now intended to increase the power of an power tool such as this, then this at the same time involves the rod housing having a larger diameter, which has a disadvantageous effect on the handling capability, since excessively large diameters can be gripped with the hand only with difficulty.